Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Attach a temperature clamp/probe to the flow pipe (right hand side, just above the overheat stat)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the burner to ignite and heat up the system.
Allow boiler to run for CH while monitoring the appliance temperature.
The boiler should operate until it gets close to MAX temperature
(approx. 75°C) then either modulate to maintain temperature or shut down.
Note:
To reduce the time for this test the heating load can be reduced
by turning off some radiators temporarily.